I think I would recommend not letting him play. Possibly call 911, or bring him to a hospital.
Hyperventilation is breathing more than you need to, breathing is usually rapid and deep. Worse that could happen is infection, bleeding, or a heart attack.
Hypoventilation is caused by multiple disorders...Alveolar hypoventilation is defined as insufficient ventilation leading to hypercapnia, which is an increase in the partial pressure of carbon dioxide as measured by arterial blood gas analysis